Abrasive article and manufacture of same



Jan. 13, 1931.

J. s. SMYSER v ABRASIVE ARTICLE AND MANUFACTURE OF SAME Original Filed Feb. 7,- 1924 2 Sheets-Sheet 1 Jan. 13, 1931. J. s. SMYSER ABRASIVE ARTICLE AND MANUFACTURE OF SAME original Filed 1924 2 Sheets-Sheet 2 Illllllllr Lula-1.11! lllllflllkttin. iii- 831.11

' terial and the support.

named an. 1am! PATENT Joel-ice arms a. mean, ornn en'rox, :u'ssacnusms masrvn' AB'HGLE m manor-Ame or em Application filed Iebrua'ry "I, 1924, Serial Io. 691,149. Renewed April 14, 1980.

This invention relates to articles of manufacture consisting of a support, and a layer of comminuted material deposited thereon;

and more particularly to producing and' maintaining the physical umon ofthe ma- The invention is es cially useful in coating strips or sheets 0 fabric, paper or the like with abrasive particles as hereinafter described in connection with. illustrative embodiment. Objects of my invention are to rovide a simple, and eflicient method of pro ucing an abrasive surface on a fabric or other article serving as a base, without materially affecting the flexibility or strength of the article; to provide an electrostatic method of continuously, and progressively producing an abrasive coating on a sheet of fabric, or other article, as it is moved in substantially the direction of its surface; to provide an improved coated fabric or other article;

. and generally to provide an improved method of and apparatus for producing an abrasive coating on an article.

In one aspect my invention contemplates electrostatically applying an abrasive coating to a fabric, or-other articleserving as a base, by electrostatically projecting abrasive particles into engagement or binding contact with the article being coated, and

then forcing the engaged particles into more intimate engagement with the article.

' In another aspect, an abrasive coatingis electrostatically applied to an electrically non-conducting article by providing a .con-

ducting path extending over the article, ap-

. plying a coating of binding material to the article, and bombarding the last applied coating by a stream of abrasive particles clectrostatically charged oppositely to the conducting path of the article.

In still another aspect, the invention provides a fabric orother article coated with a conductin material having a superposed coating 0 binder material upon which there is deposited a coating of granular material.

Thearticle, when in sheet form, may be coated by moving the sheet continuously in substantially the direction of its surface; dipping a portion of the sheet into a liquid making a sliding contact between the conducting portionof the sheet and one terminal of a .source of electromotive force; dipping the sheet in a liquid bath of binding material to leave a coating of the binder on the sheet; equalizing the distribution of the binder coating on the sheet; moving the sheet through a stream ofabrasive articles which .are electrostatically charge by the source of electromotive force with a sign opposlte to that of the conducting path of the sheet; equalizin the distribution of abrasive particles over t e surface of the sheet, and

forcing the particles into more intimate enconnection with the accompanying drawings', in which 1 is an elevation, in section diagrammatically showing apparatus for preparing an abrasive coating on a sheet of fabric;

F 2 is a plan of a portion of Fig. 1;

Fig. 3 is an enlarged view of a port-idn of Fig. 1;

Figs. 4, 5, 6 and 7 are cross sections of a fabric in successive stages, respectively, of the coating operations.

In Fig. 1 the sheet A of fabric, paper, or similar material, is moved substantially in the direction of its surfaceand directed b rollers so that it passes continuously throug a series of zones B, C, D and E, in each one of which, the sheet is subjected to a different or comminuted graphite or other conducting material. The liquid is preferably non-corrosive and without appreciable physical or chemical effect upon the sheet when used primarily to suspend the conducting particles; it may be water or other suitable liquid. The sheet passes between the rollers 14 which remove the excess of the mixture from the sheet, resulting in a substantially uniform distr bution of conducting material throughout. The rollers 15 direct the sheet through a drying zone 0 within the chamber 16, having a heating element 17, such as a steam pipe, or other heater. The liquidupon drying from the coating on the sheet leaves the conducting material distributed over the surface as a conducting path. The brush 18 in contact with the sheet is connected to the positive terminal of the source of electromotive force 19 which electrifies the conducting path of the sheet with a charge of positive If t ollers 20 direct the sheet through the zone D, in which, a coating of binding material is applied to the sheet as it dips into the liquid bath 21 of binding material, such v as parafiin, or other suitable binder, preferably electrically nonconducting, in tank 22, heated by a steam pipe (not shown), or other suitable means. The rollers 24 remove the excess liquid and distribute the coating uniformly over the surface to equalize its thickness.

In the zone E, a coating of abrasive is electrostatically applied to the sheet. The hoppers 30'for'containing abrasive particles of emery, carborundum, pumice, or other suitable abrasive material having the size of particle with which it is desired to coat the sheet, discharge through spouts 31 into the cylindrical electrifying chambers 32, preferably of electrically insulating material, disposed on opposite sides of the upwardly moving sheet. The nozzles 33 discharge air into the conduits 34 (see Fig. 3), these conduits having apertures which admit the moving air at suitable pressure to the abrasive container to produce a condition in which the abrasive particles are temporarily suspended in the atmosphere of the container through orifices 38-into the zone of the electrical discharge, which takes place between the needles 37 mounted on bus-bars 36 and the conducting sheet.

Bus bars 36 are connected preferably to the negative terminal of source of electromotive force 19 by means of leads 39, the effective potential of the source 19 being adjusted to such a value, e. g. 18000 volts, more or less, that the abrasive particles in chamber 32 become electrified with a negative charge, and together with the air admitted through nozzle 33 discharge through slot 38 as a stream of electrified particles which are eletrostatically propelled toward the positively charged sheet A, the solid particles bombarding and coming into engagement with the binder coating on the sheet. It will be seen that the electrostatically propelled abrasive particles emerging from each of the oriabrasive particles from the air before entering the conduit. Air free from ab-ra sive particles is admitted through openings 43. 44 and 45, thus tending to clarify the air within the hous ng and together with the air discharged through slots 38 causing a flow of the air and drift of the abrasive particles around the baflle diaphragms 46 asindicated by the arrows, the baflles tending to cause a precipitation of the particles at one end of the housing as indicated by the accumulation 47 which also includes the abrasive sifted by the screen 42. Owing to the reduced air pressure in housing 40 when air is exhausted through conduit 41, air may be fed through nozzles 33 directly from the atmosphere, but if a greater flow is desired compressed air may be fed through these nozzles.

Rollers 48 between which the sheet passes, after being coated with the abrasive, equalizes the distribution of abrasive material on the surface of the sheet and forces the abrasive particles intomore intimate engagement with the sheet which then passes upward and is wound on the roll 49. The'sheet may be propelled by rotation of the roll 49 or one or more of the rollerswith which the sheet contacts between rolls 10 and 49.

Figure 4 shows the appearance of a simple fabric sheet A, of electrically insulating or poorly conducting material, having a warp 50 and a woof 51, before the sheet has entered the coating zone B. Fig. 5 shows the particles 52 of graphite or other conductor distributed over the surface of the fabricafter the liquid from the batch 12 has been evaporated from the surface in the drying zone C and before the sheet has entered the coating zone D. Fig. 6 shows the sheet A with the coatin 53 of paraffin, or other binding ma terial. efore the sheet enters the coating zone progximately one particle thick to a thick deposit, and in any case the particles aredistributed with great uniformity. B coating the fabric u on both'sides its. use lness is practically oubled and b virtue of the roughness of the rear side t e article canbe used more effectively with less danger of slippage in the fingers.

While certainmaterials have been mentioned in disclosing an example of how the invention may be carried out, it is to be'understood that the materials specifically named are not necessary to the invention but may be replaced by other suitable materials. It is obvious that the sheet may be treated in'the various zones B, C, D and E by va-'- rious modifications of the apparatus disin the art.

closed within the knowledge of those skilled The method, and apparatus disclosed for carrying out the method, permit of produc mg an abrasive coating on sheet fabric or other articles,'particularly those in which it means for coating the moving sheet witlra" conducting material, means for applying a coating of binder material over said conducting coating, and means for electrostatically 4 electrically non-conducting sheet material,

bombarding the binder coating with electrically charged particles to produce a coating upon said binder coating.

2. pparatus for applying coatings to comprising means for propelling the sheet v substantially in the direction of 1ts surface,

means for applying to the sheet a coating of liquid having conducting particles in suspension, means for drying the liquid to leave conducting particles as a coating on the sheet, means for-applying a coating of binder material to the sheet, and means for electrically projecting a stream of granular matter into engagement with the binder coating to apply a superficial coating to the sheet.

. 3, The method of electrostatically depositing a coating upon an article comprising ag1- tating granular matter in the presence of an electric field, confining movements of the agitated particles to a restricted zone, and

electrostatically projecting the electrified particles outwardly from the restricted zone to the object to be coated. l

4:. The method of preparing an abrasive coating on fabric'or similar material, which comprises continuously moving the sheet in substantially the direction of its surface, provelgdipping the sheet in a liquid hath aving ely divided conducting materialin suspension, drying upthe liquid left asa coatin on the sheet and leaving thesuspende particles deposited on the sheet to form a conducting" ath over'the surface'oi the sheet, coatin t a sheet with a binder, equalizing the thlckness of the bindercoating, electrostatic'ally projecting astream of abrasive particles against the sheet,-and forcing the abrasive particles. into closer engagementwith the sheet. a a

5. The method of pre aring an {abrasive coating on a sheetjof fa ricer similar ma terial, which 001115313863 moving thesheet sub st'antiallyin the ection' of its surface, dip- 4 ping-the sheet in a liquid bathhaving com minuted conducting'material in suspension, drying up the liquid left as a coating-on. the

sheet and leaving the suspended materialde,

posited to form a conducting ath over the surface of the sheet, vdipping t e sheet in a bath of liquid binding material, and'electrostatically depositing a coating of abrasive particles on the binder. "f I 6. The method of reparing an abrasive coating on a sheet of abric or similar material, which comprises passing the sheet through a liquid having comminuted conducting materlal in suspension, withdrawmg the sheet from the liquid 'and dryingfifthe liquid to leave a coating ofsconductingmat'e' rial on the sheet, coating the sheet witha binding material, and electrostatically projectin with t e coating of binding materlal.

7. The method of preparing .an abrasive coating on a sheet ofafabric or similar ma; terial, which comprises coating the sheet with an electrically conducting material electrostatically pro ecting abrasive particles I into engagement with thesheet and forcing the engaged abrasive particles into more lindtimate engagement with the sheet. 1 8. The method of reparing an abrasive coating on a sheet of abric or similar'material, which comprises continuously moving vthe sheet in substantially the direction of its surface progressively coating the sheet with a liqui terial in suspension, progressively drying the liquid to leave the suspended material-as a conductive coating on the sheet, progressivel coating the sheet with a bindlng materia, and progressively bombardingthe sheet with a stream of abrasive. particles electrically charged oppositely to the conducting coating ofthe sheet. "7 f1 9. The method of pre aring an abrasive coating on a sheet of fa ric or" similar ma terial, which comprises continuously moving the sheet in substantially the direction of its, surface, progressively depositin r 'on;

ducting coating on the sheet, projecting-'9. v

stream ofabrasive particles electrified oppoabrasive particles into engagement having comminuted conducting ma-v iso . gaged abrasive engagement wit ment with the sheet, and securing the enthe sheet. 10. The method of preparing an abrasive coating on an electrically non-conducting base, which comprises coating the base wit an electrically conducting material coating.

the conductinv'material with a bin ng material, and dlectrostatically projecting a stream of abrasive particles into engagement with the binder coating.

11'. The method of making an abrasive article which-comprises rendering a sheet of fabric or the like both conductive and adhesive and by oppositely charging the conduc-' tive sheet and comminuted abrasive material adjacent thereto, electrostatically depositing a layer of said material upon the adhesive surface thereof.

12. The method of coating a sheet of material with abrasive particles which comprises rendering the sheet both conductive and adhesive and, by oppositely charging the conductive sheet and abrasive particles in the region of the sheet, electrostatically depositing the abrasive particles upon the adhesive surface of the sheet. 7

- 13. The method of coating a sheet of material with abrasive particles which comprises rendering the sheet both conductive and adhesive, continuously agitating a supply of. abrasive particles in an enclosed region, continuously feeding the sheet along a path associated with said region, and byoppositely charging the conductive sheet and a rasive particles in said region electrostatically embedding the particles upon the adhesive surface of the sheet.

14. Apparatus for'applying adhesive material to an electrically conducting surface and depositing thereon finely divided particles under the influence of an electrostatic field, comprising means for moving the surface in substantially the direction of its length, means for applying adhesive material to the surface, and means for electrostatically bombarding the adhesive material with elec trically charged particles to produce a coating upon said adhesive material.

15. Apparatus for applying finely divided particles. to a surface previously rendered electrically conducting and adhesive, com prising means for producing an electrostatic field in a region containing finely divided particles and means for moving the surface through said electrostatic field.

16. The method of electrostatically depositing finely divided material particles upon an article, which comprises establishing an electrostatic field, dispersing the finely divided material particles to form a suspension in a region containing the electrostatic field, confining movements of said particles to a lparticlesinto more intimate:

1,1ae,eoo

restricted zone and electrostatically project 1 coatin on a sheet of fabric .or similar material w ich comprises treating the sheet to render it electrically conductiveand mechanicall adhesive, establishing an electrostatic fiel of force between the surface to be coated and a charged conductor of opposite polarity to that'of the sheet and adjacent thereto, conveying finely divided abrasive particles into the electrostatic field of force and moving the surface progressively and in substantially its own plane through the electrostatic field of force whereb the abrasive particles may, by the action 0 the electrostatic field of force upon them, be deposited thereon.

' 18. The method of spreading a'coatin of finely divided particles on a sheet of fa ric or similar material which comprises treating the sheet to render it electrically conductive and mechanically adhesive, establishing an electrostatic field of force between the surface to be coated and a charged conductor of opposite polarity to that of the sheet and adj acent thereto, conveying the finely divided particles into the electrostatic field of force, and

moving the surface progressivelyv and in substantially its own plane through the electrostatic field of force whereby the finely divided particles may, by the action of the electrostatic field of force upon them, be deposited thereon.

19. Apparatus for depositing finely divided particles on the surface of a fabric or other material comprising means for treating the fabric to render it electrically conductive and mechanically adhesive, means for establishing an electrostatic field of force between two electrodes of opposite polarity one of which is in electrical contact with the surface of the fabric, means for conveying the finely divided particles into the electrostatic field of force Where, under its influence, they will be deposited on the surface of the fabric, and means for progressively moving said surface in substantially the direction of its length.

20. Apparatus for depositing finely divided abrasive particles on the surface of a fabric or other material comprising means for treating the fabric to render it electrically conductive and mechanically adhesive, means for establishing an electrostatic field of force between two electrodes of opposite polarity one of which is in electrical contact with the surface of the fabric, means for conveying the ,finely divided abrasive particles into the electrostatic field of force where, under its influence, the will be deposited on the surface of the fa ric, and means for progressively moving said surface in substantially the conductive and mechanically adhesive com-.

rising establishing an electrostatic 'field of orce between two electrodes of opposite polarity one of which is in electrical contact with the surface to be coated,-conveying the pulverized material .into the electrostatic field of force under the action of which it will be translated to the surface to be coated,

and subjecting successive parts of the surface to the combined action of the electrostatic field of force and the a manner that will tinuous. v

22. The method of coating, with finely divided abrasive material; a surface that is e substantially conboth electrically conductive and mechanically adhesive comprising establishing an electrostatic field of force between two electrodes of opposite polarity one of which is in electrical contact with the surfaceto be coated, conveying the finely divided abrasive material into the electrostaticfield of force under the action of which itwilll be translated to the surface to be coated, and subjecting successive parts of the surface to the combined action of the electrostatic field of force and the finely divided abrasive material in a manner thatwill be substantiallycontinuous.

23. The method of spreading a coating of finel divided material upon an electrically cond fictive surface, which comprises estab- 'lishin an electrostatic field of force between two e ectrodes of opposite polarity, one of which is in electrical contact with the surface to be coated, conveying the finel divided 'ma-' terial into the electrostatic fiel of force under the actiorrof which it will be translated to the surface to be coated, and bonding the finely divided material to the surface to be coated.

Signed b me at Boston,-Massachusetts, this 15th day 0 J anuary, 1924.

JAMES s. SMYSERQ ulverized, material in 

